I am trying to map a variable onto a stl file with ResampleWithDataset with a Python-Script (client  server). The problem is that it always maps all the variables (I have 25). One variable takes about 2 minutes and because of that resamplewithdataset takes about 60minutes.
So I have tried to load only the desired variables:
Mesh = OpenFOAMReader()
Mesh.FileName =  case.foam
Mesh.CellArrays = [U, p]
UpdatePipeline()
Now I check which variables are loaded:
Mesh.CellArrays.Available
>>> [U,p]
this is ok. But if I check the vtkMultiblockDataset I see that all variables are loaded:

data = servermanager.Fetch(Mesh)
print data
>>>

Cell Data: Debug:Off ModifiedTime:560721 Reference Count:1 RegisteredEvents(none) Number Of Arrays: 24 Array 0 name = U Array 1 name = p(...) Array 22 name = UMean Array 23 name = pMean
How can I avoid to load all variables? Or how can I define, that only one variable is mapped?